Piezoelectric flash lamp ignition



United States Patent 1 1 Haugsjaa et al.

[ 1 PIEZOELECTRIC FLASH LAMP IGNITION [75] Inventors: Paul 0. Haugsjaa,Acton; Daniel C.

Casella, South Hamilton. both of Mass.

[73] Assignee: GTE'Laboratories Incorporated,

Waltham, Mass.

[22] Filed: June 17, 1974 [21] Appl. No.: 479,701

Related U.S. Application Data [63] Continuation-impart of Ser. No.330,557, Feb. 8,

1973. abandoned.

[52] U.S. Cl. 431/98; 310/87, 317/D1G. 11; 431/255 [51] Int. Cl ..H01v7/00 [58] Field of Search. 431/98, 255; 317/81, DIG. 11; 310/83. 8.7;240/].3; 354/135 [56] References Cited UNITED STATES PATENTS 2,972,9372/1961 Suits 431/255 X 3.585.417 6/1971 Hclfen 431/255 X 3.732.0585/1973 Ort et a1. 3.771.943 11/1973 Schlamp 431/255 Iv (Mk R17 Ml/fl'fl[451 Apr. 29, 1975 FOREIGN PATENTS OR APPLICATIONS l,186 143 4/1970United Kingdom 310/81 Primary Examiner-William F. ODea AssistantExaminer-Harold Joyce Attorney, Agent, or Firmlrving M. Kriegsman;Bernard L. Sweeney 1 1 ABSTRACT Aphotographic flash lamp igniterutilizing piezoelectric elements as high voltage generating meanscomprisises two parallel piezoelectric elements, impact caps andmechanical linkage. ln synchronization with the shutter of a camera,striking hammers hit two impact caps which activate two piezoelectricelements arranged in parallel. The electrical energy created by thepiezoelectric crystals is transferred efficiently to ignite aphotographic flash lamp electrically connected across the piezoelectricelements. However, the net kinetic energy seen by the supportingstructure is essentially zero.

5 Claims, 1 Drawing Figure PIEZOELECTRIC FLASH LAMP IGNITIONCROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of our earlier application. Ser. No. 330.557. filedFeb. 8. I973. now abandoned.

BACKGROUND OF THE INVENTION This invention relates to piezoelectricvoltage generators and. in particular. to a piezoelectric generator forigniting photographic flash lamps.

Conventionally. the energy for ignition of photographic flash lamps usedin portable photographic equipment is obtained from batteries installedin the flashgun or camera. However. batteries are not entirelysatisfactory since they deteriorate with use and time, and must bereplaced at relatively frequent intervals. Piezoelectric generators havebeen proposed as a replacement for batteries since they are capable ofproducing a large amount of energy, have a life commensurate with therest of the camera and remain relatively stable in performance withoutsignificant loss of voltage or electrical capacity.

In one system disclosed by the prior art. a piezoelectric element ismechanically stressed and the electrical energy generated thereby storedin a capacitor. The charge in the capacitor is then discharged into aphotographic flash lamp by connecting the capacitor directly across thelamp. This system is disadvantageous in that it requires a capacitor,which must be charged before lamp ignition can take place.

Another known method involves using sheets of pi ezoelectric materialarranged as a flexible cantilevered beam structure. When the unsupportedend of the beam is displaced and released. the beam reboundsmomentarily. touching an electrical contact at the point of maximum beamdisplacement. The piezoelectric material is delivered to the lamp whenthe beam rebounds and contacts the lamp terminals. This method requiresa large, bulky enclosure to permit the movement of the beam.

Accordingly, we have invented a piezoelectric flash lamp igniter whichdoes not employ a capacitor or other external storage elements yettransfers energy efficiently into the photographic flash lamp.Furthermore. the present invention is compact and does not require alarge container to enclose and activate the piezoelectric elements.

SUMMARY OF THE INVENTION In the present invention, two smallpiezoelectric crystals are arranged end to end and electricallyconnected in parallel. When a mechanical mechanism such as a shutterrelease is initiated. two striking members or hammers fall in unison andthe force of the impact created thereby is delivered simultaneously toboth piezoelectric elements. The hammers strike two impact caps orimpact receiving members which contact and distort the piezoelectriccrystal elements arranged therebetween. The other end of thepiezoelectric crystals are in common relation to an electrode. When theimpact receiving member is struck by the hammer in the above manner. thepiezoelectric elements are distorted to generate a high voltage betweenthe confronting positive ends of these elements. The thus generated highvoltage is transmitted through the common conducting metal plateelectrode and a resistor of conductive coupling to an anode terminal ina photographic flash lamp socket. The cathode of said flash lamp socketis connected to a common ground potential; therefore, when the voltageis generated by the piezoelectric crystal. it is delivered immediatelythrough the socket of the flash lamp. thereby igniting the photographicflash lamp. As previously indicated. the sequence is initiated by amechanical mechanism such as a shutter release. which may besynchronized with the flash lamp ignition for proper photographicexposure. The use of two piezoelectric crystals being strucksimultaneously at opposite ends creates no net force to be transferredto the camera body. This avoids shaking the camera and the possibilityof blurring the photograph.

The features of the present invention which are believed to be novel areset forth with particularity in the attendant claims. The invention.together with further advantages thereof. may best be understood byreference to the following description taken in connection with thedrawing.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a crosssectional view ofthe flash lamp igniter in accordance with the present invention.

PREFERRED EMBODIMENT OF THE INVENTION The present invention will now bedescribed referring to the accompanying drawing in which a preferredembodiment of the piezoelectric photographic flash lamp igniter inaccordance with the present invention is illustrated.

The piezoelectric ignition system. 15, in accordance with the presentinvention. is shown in detail in the FIGURE. This system may be locatedwithin a camera (not shown) or in a separate unit associated with flashlamp I3 (as shown in the FIGURE). The ignition system includes a pair ofpiezoelectric elements such as polarized lead-zirconate-titanate ceramicin a horizontally aligned relation in a horizontally extending hollowcylindrically insulative member 18. The pair of piezoelectric elements16 and 17 are horizontally aligned having the adjacent positive endsthereof facing each other with a conductive metal plate 20 extendingthrough the adjacent wall of the cylindrical member 18 andlongitudinally along the outside of cylindrical member I8. The metalplate 29 is electrically connected in series to a conductive connectoror ballast resistor 21 which is connected to the anode of thephotographic flash lamp l3 by an insulated wire 22. The cathode of thephotographic flash lamp 13 is electrically connected to the casing I4.An impact receiving cap 25 is secured to the left side of the leftelement 16 and the cap is adapted to receive an impact from an impactdevice which will be described hereinafter. A second impact receivingcap 26 is secured to right side of the right element 17 and the secondcap is adapted to receive an impact from an impact device which will bedescribed hereinafter.

The impact device may be actuated by an actuating member or a camerashutter release button 11 having a shaft and flanged end 11'. Acylindrical spiral return spring 29 is anchored to the base of the shaftof the bottom II near the flanged end 11'. The other end of spring 29 ismounted to the casing 14, normally urging the release button llupwardlyv Thus a portion of the release button I1 is normally disposedoutside of the casing 14. A right striking member 30 is pivotablysupported on the transverse shaft 31 extending between opposite sidewalls of casing 14 and secured at the opposite ends to the interior ofthe casing. A tension spring 32 is disposed on the transverse shaft 3]with one end abutting against a laterally extending pin (not shown) onthe striking member 30 and the other end secured to the interior of thecasing [4 by a transverse pin 35 fixedly mounted on the inside of thecasing. Therefore. the right striking member 30 is adapted to pivotabout transverse shaft 31 toward and away from the above-mentionedimpact receiving member 26. A left striking member 40 is pivotablysupported on the transverse shaft 41 extending between opposite sidewalls of the casing 14 and secured at the opposite ends to the interiorof the casing. A tension spring 42 is dis posed on the transverse shaft41 with one end abutting against a laterally extending pin (not shown)on the striking member 40 and the other end secured to the interior ofthe casing 14 by a transverse pin 43 fixedly mounted on the inside ofthe casing. Therefore, the left striking member 40 is adapted to pivotabout transverse shaft 41 toward and away from the above-mentionedimpact receiving member 25. Two angulated stop arms 50 and 51 havingelbows 50' and 51' and fingers 50" and 51" are pivotably supported ontransverse shafts 31 and 41 respectively. The outer portion of theelbows 50 and contact transverse tripping pins 57 and 58 respectivelywhich are fixedly mounted on the striking members 30 and 40respectively.

Therefore, when activating member ll is depressed downward, the stoparms are pivoted outwardly forcing the striking members outwardly also.When the member 11 reaches its lower limit of travel, as represented bythe dotted position 60, the fingers 50" and 51" no longer are engaged bythe lower surface of member ll. Springs 52 and 53 operate to quicklyrotate stop arms 50 and 51 back toward the original position. Since theelbows no longer engage the tripping pins, the striking members 30 and40 are released and fall against the im pact receiving members 26 adn25, respectively. After the downward pressure is removed from member 11,spring 29 urges the member 11 upward. When the release approaches anupright rest position, the stop arms re-engage their respective trippingpins. In operation, when the shutter release button or actuating member[I is first manually pushed downward in the arrow direction (shown inthe FIGURE) against the force of the spring 29, the spring 29 having oneend anchored to the inside of the case 14 and the other end thereofanchored to the flanged end of the actuating member, the spring 29 isstretched so as to store the moving or pushing energy of the member 1]in the spring 29. The movement of a member 11 actuates the shutter of acamera (not shown) in a conventional manner as well as synchronouslyactuating the flash lamp igniter which is described hereinafter. As themember 11 is pushed further in the above arrow direction, the flangedportion thereof forces the pivot arms 50 and 51 about shafts 31 and 41respectively in the arrow directions (shown in the FIGURE). The elbowportions of the pivot arms 50 and 5] engage stop pins 57 and 58respectively and thereby force the striking members 30 and 40,respectively, to pivot about shafts 3] and 41, respectively, against theforce of tension springs 32 and 42, respectively, until the elbowdisengages from stopping pins upon release by member 11 whereupon thestriking members 30 and 40 are allowed to rapidly descend inwardly tostrike against the impact receiving members 26 and 25, respectively. Inthe above manner. the piezoelectric elements 16 and 17 are distorted togenerate a high voltage between the confronting posi- 5 live ends ofthese elements. The thus generated high voltage is transmitted throughthe conductive metal plate 20, resistor or conductive coupling 2], andinsulated wire 22 to the anode of photographic flash lamp 13 which isignited thereby. AS the actuating member It) It is returned to itsnormal position in the manner as mentioned above, the pivot arms 50 and51 are also allowed to pivot about transverse shafts 31 and 4] contra tothe arrow direction (shown in the FIGURE) to the extent necessary forthe member II to return to its normal position.

The various features and advantages of the invention are thought to beclear from the foregoing description. Various other features andadvantages not specifically enumerated will undoubtedly occur to thoseversed in the art, as likewise will many variations and mofifications ofthe preferred embodiment illustrated, all of which may be achievedwithout departing from the spirit and scope of the invention as definedby the following claims.

What is claimed is:

l. A piezoelectric photographic flash lamp igniter comprising an outercasing,

a socket having a pair of electrodes for receiving a photographic flashlamp therein being attached to and insulated from the outer casing,

a piezoelectric high voltage generating device disposed within andattached to the outer casing, the device comprising a pair ofsubstantially identical piezoelectric elements positioned end to end,the abutting ends being ofa like polarity and being commonlyelectrically connected to a first one of the pair of electrodes, and

a pair of conductive impact receiving caps being in mechanical andelectrical engagement with the other opposing end of each of thepiezoelectric elements, the caps being electrically coupled to the otherof the pair of electrodes,

means for simultaneously impacting each of the impact receiving caps onthe piezoelectric elements with a force which is equal to and in theopposite direction of the force applied to the other impact receivingcap so that a high voltage signal is applied across the photographicflash lamp to cause ignition thereof, and the net kinetic energytransferred to the outer casing is substantially zero, and means foractuating the impacting means.

2. A piezoelectric photographic flash lamp igniter according to claim 1,wherein the means for impacting comprises an opposed pair ofsubstantially identical force generating assemblies each of whichcomprises a shaft affixed to the outer casing,

an elongated striking member pivotably positioned 60 on the shaft so asto reach the respective impact receiving cap, means for rotating thestriking members away from the impact receiving cap, an impact forcestoring spring engaging the striking member so that as the strikingmember is rotated away from the impact receiving cap energy is stored inthe spring, and

means for releasing the striking member so that it is rapidlycounterrotated toward and against the impact receiving cap to cause ahigh voltage to be applied across the photographic flash lamp.

3. A piezoelectric photographic flash lamp igniter according to claim 2.wherein the means for actuating the impacting means comprises anoutwardly spring biased. extended release member slidably mountedthrough the outer casing and having an outwardly flared portion at theinternal end forming a cam surface at the internal end thereof. and

wherein each striking member has a protuberant generally pointedfollower thereon which engages the flared cam surface on the releasemembers so that as the release member is slid inwardly the cam surfaceforces the striking members to rotate away from the impact receivingcaps until the continued inward travel of the release member causes thecam surface-follower engagement to terminate thereby releasing thestriking members.

4. A piezoelectric flash lamp igniter according to claim 3, wherein thepiezoelectric high voltage generating device further includes aninsulative hollow cylindrical member in which the pair of piezoelectricelements are arranged with the positive ends thereof abutting each otherand having a conductive metal plate disposed therebetween.

5. A piezoelectric photographic flash lamp igniter according to claim 4.which further includes a ballast rcsistor connected in series with thepiezoelectric elements.

1. A piezoelectric photographic flash lamp igniter comprising an outercasing, a socket having a pair of electrodes for receiving aphotographic flash lamp therein being attached to and insulated from theouter casing, a piezoelectric high voltage generating device disposedwithin and attached to the outer casing, the device comprising a pair ofsubstantially identical piezoelectric elements positioned end to end,the abutting ends being of a like polarity and being commonlyelectrically connected to a first one of the pair of electrodes, and apair of conductive impact receiving caps being in mechanical andelectrical engagement with the other opposing end of each of thepiezoelectric elements, the caps being electrically coupled to the otherof the pair of electrodes, means for simultaneously impacting each ofthe impact receiving caps on the piezoelectric elements with a forcewhich is equal to and in the opposite direction of the force applied tothe other impact receiving cap so that a high voltage signal is appliedacross the photographic flash lamp to cause ignition thereof, and thenet kinetic energy transferred to the outer casing is substantiallyzero, and means for actuating the impacting means.
 2. A piezoelectricphotographic flash lamp igniter according to claim 1, wherein the meansfor impacting comprises an opposed pair of substantially identical forcegenerating assemblies each of which comprises a shaft affixed to theouter casing, an elongated striking member pivotably positioned on theshaft so as to reach the respective impact receiving cap, means forrotating the striking members away from the impact receiving cap, animpact force storing spring engaging the striking member so that as thestriking member is rotated away from the impact receiving cap energy isstored in the spring, and means for releasing the striking member sothat it is rapidly counterrotated toward and against the impactreceiving cap to cause a high voltage to be applied across thephotographic flash lamp.
 3. A piezoelectric photographic flash lampigniter according to claim 2, wherein the means for actuating theimpacting means comprises an outwardly spring biased, extended releasemember slidably mounted through the outer casing and having an outwardlyflared portion at the internal end forming a cam surface at the internalend thereof, and wherein each striking member has a protuberantgenerally pointed follower thereon which engages the flared cam surfaceon the release members so that as the release member is slid inwardlythe cam surface forces the striking members to rotate away from theimpact receiving caps until the continued inward travel of the releasemember causes the cam surface-follower engagement to terminate therebyreleasing the striking members.
 4. A piezoelectric flash lamp igniteraccording to claim 3, wherein the piezoelectric high voltage generatingdevice further includes an insulative hollow cylindrical member in whichthe pair of piezoelectric elements are arranged with the positive endsthereof abutting each other and having a conduCtive metal plate disposedtherebetween.
 5. A piezoelectric photographic flash lamp igniteraccording to claim 4, which further includes a ballast resistorconnected in series with the piezoelectric elements.